RU2265135C2 - Device for starting and feeding electric arc-jet plasma engine - Google Patents

Abstract

FIELD: electric arc-jet engine units, plasma accelerators, and generator units.

SUBSTANCE: converter cells are divided into two groups. All cells limit discharge current under short-circuit conditions. In addition, cells of one group regulate discharge voltage and those of other group stabilize cathode heater current; operation thresholds with respect to discharge current are different for all cells so that only one cell may be run in limiting mode at a time.

EFFECT: reduced input current ripples and noise, input filter mass, and maximal power requirement of device.

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Description

The invention relates to electro-reactive technology, namely to electro-reactive propulsion systems based on plasma accelerators.

A device for powering an electroreactive plasma engine is known [1], the disadvantage of which is the increased weight and size indicators due to the presence of separate converters for powering the cathode heater and the ignition electrode, which include a power inverter, a rectifier, matching transformers and a control system, as well as increased ripple current consumption and interference.

A device for starting and powering an electro-reactive plasma engine [2], comprising a common converter, consisting of n unregulated converter cells connected in parallel to the input and output, current generators of the cathode heater and firing pulses. The disadvantage of [2] is the increased power consumption due to the absence of current limits during a short circuit in the load, as well as the presence of matching transformers, which leads to an increase in weight and size indicators.

Closest to the claimed is a device for starting and powering an electro-reactive plasma engine [3], containing one common converter, consisting of parallel-operating converter cells, each of which contains, in addition to a high-voltage winding for supplying a discharge, another low-voltage coil for supplying a cathode heater and an ignition electrode. The input cells are connected in parallel, and the output cells are connected in series. The disadvantage of this device is the large ripple and interference caused by the interruption of the input current of all cells at the same time, which is why it is necessary to increase the mass of the input filter.

The purpose of the invention is to reduce the maximum power consumption, the level of electromagnetic interference and the mass of the device.

This is achieved by the fact that the converter cells are divided into two groups, in each of which the high-voltage outputs are connected in series, and the low-voltage outputs, available only in the cells of the second group, are connected in parallel, one stabilizes the discharge voltage, and the other stabilizes the current of the cathode heater, and for stabilization of the current of the cathode heater, the input current of the second group of cells is interrupted at the same time, however, at this time there is no discharge current, therefore, the amplitude value of the consumption current does not exceed 15% of the calculated (figure 1) (0-t ₁ ), and therefore, does not cause significant ripple and interference. When increased conductivity appears in the discharge channel, only one of n cells switches to the control mode; for this, the thresholds of the cells for the discharge current are selected as follows:

where i is an integer from 1 to n (the number of cells);

I _r.max - the maximum allowable discharge current in the limiting mode.

If discharge current

then in the control mode there will be the i-th cell, while the cells whose number is less than i are fully open, and the cells with numbers greater than i are closed.

The diagram of the current consumption in this mode has the form shown in figa (t ₁ -t ₂ ), and the discharge current in fig.1b (t ₁ -t ₂ ). In the inventive device, the maximum power consumption in the short circuit mode in the load is less than in [3], and can be further reduced by increasing the number of cells.

After burning excess gas in the discharge chamber, the discharge channel conductivity decreases and the regulatory effect on the discharge current is stopped, and the ripple of the current consumption is caused only by the regulatory effect on the discharge voltage (t ₂ ...), carried out on a group of cells, the number of which is determined from the ratio:

where n is the number of cells in the group that performs the stabilization of the discharge voltage,

m is the number of cells in the group performing stabilization of the current of the cathode heater,

m + n = p is the total number of cells of the Converter.

Thus, in the mode when the current consumption is close to the nominal, its ripple is determined by the ratio of I _nom / p, i.e. p times smaller than in [3], and since the mass of the filter is proportional to the ripples of the current consumption, it will also decrease significantly.

The device for starting and powering an electro-reactive plasma engine (Fig. 2) contains DC busbars 1, an input filter 2, a master oscillator 3, the signals from which are fed to the inputs of the converter cells 4 ₁ ... 4 _n and 5 ₁ ... 5 _n , threshold devices 6 ₁ ... 6 _{n + m} , having different thresholds for operation according to the discharge current, the outputs of which are connected to the inputs of the converter cells. The outputs of the converter cells 4 ₁ ... 4 _{n are} connected to the primary windings of the transformers 7 ₁ ... 7 _n having only a high-voltage secondary winding for powering the discharge, and the outputs of the cells 5 ₁ ... 5 _{m are} connected to the primary winding of the transformers 8 ₁ . ..8 _m , having, in addition to the high-voltage still low-voltage winding for powering the heaters of the cathodes HK ₁ , HK ₂ and ignition electrodes EP ₁ , EP ₂ . The high-voltage windings of all converter cells are connected to the inputs of the voltage-summing rectifier 9, the outputs of which are connected to the anode A and the common point of the cathodes K ₁ , K _{2 of the} motor 12 through the limiting inductor 10, the magnetic coil MK and the current sensor 11, and the low-voltage windings m of the cells connected to the inputs of the current-adding rectifier 13, the outputs of which through the metering choke 14, a key 15 or 16, controlled by the control unit 17, and the current sensor of the cathode heater 18 are connected to the cathode heaters HK ₁ , NK ₂ and common point th cathodes. The external control unit 17 receives external commands and a signal from the discharge current sensor 11, through which control signals are generated for the master oscillator 3 and keys 15, 16. The secondary winding of the metering inductor 14 is connected to the common point of the cathodes at one end and 19 s to the other an anode and a filtering capacitor 20, in parallel with which a discharge voltage sensor 21 is connected, and through diode diodes 22 and 23 with ignition electrodes of EP ₁ and EP _2, respectively. To generate ignition pulses in the pickup mode, a key 24 is added, made on the basis of a field-effect transistor, which is connected by a drain to the output of the metering inductor 14 and keys 15 and 16, and the source through the diodes 25, 26 to the ignition electrodes, the gate is connected to the control unit 17 With one input, all threshold devices are connected to the discharge current sensor 11, and the other 6 ₁ ... 6 _{n are} connected to the discharge voltage sensor 21, and 6 _{n + 1} ... 6 _m to the current sensor of the cathode heater 18.

The device for starting and powering an electroreactive plasma engine (figure 2) works as follows. When a command is received to turn on the cathode heater HK ₁ (or HK ₂ ), the control unit 17 closes the circuit of the corresponding cathode heater with key 16 (15). Then a command is given to turn on the converter, and the master generator 3 starts working, which starts the converter cells 4 ₁ ... 4 _n and 5 ₁ ... 5 _m , connected to the power buses 1 through the input filter 2. At the same time, on the transformer windings 7, 8 a voltage appears, which is summed in the rectifier 9, due to the serial connection of the high-voltage windings 7 and 8, and through the limiting inductor 10 is fed to the anode A, capacitor 20 and discharge voltage sensor 21, the signal from which is fed to the inputs of threshold devices 6 ₁ ... 6 _n . At the same time, voltage appears on the low-voltage windings of transformers 8 ₁ ... 8 _m , which are summed over the current in the rectifier 13, and a current appears in the NK circuit. Until the heater current reaches the required level, the signal from the sensor 18 is less than the threshold 6 _{n + 1} ... 6 _{n + m} , and if the discharge voltage does not exceed the permissible level, then all threshold devices at the output have an enable signal, and all the converter cells work on a full loop (the duty cycle of the output pulses is close to unity). If the discharge voltage exceeds the permissible value (due to increased supply voltage or non-ideal rectangular pulses at the output of the rectifier 9), then one of the cells 4 ₁ ... 4 _n goes into control mode, while cells 5 operate in a full loop. If the glow current becomes greater than the permissible value, then all cells 5 go into the control mode, since 6 _{n + 1} ... 6 _{n + m} have one threshold for the NC current. There is no discharge current in this mode, and the channel A - K conductivity is determined only by the leakage current of the capacitor 20 and divider 21. After some time, when the cathode heater warms up, the control unit 17 generates a signal, opening key 16 (15) and closing 24. In this case, the current of the cathode heater is transformed into the secondary winding of the metering inductor 14, the voltage of which is determined by the conductivity of the gas gap EP - K, and the diodes 25, 26 are locked by the higher potential of the cathodes of the diodes 22 and 23. If conductivity occurs at the moment veniya pulse voltage on a secondary winding of the choke 14 has remained close to zero (the breakdown has not occurred), the inductor energy is discharged through the diode 19 in the capacitive energy store, which also acts as a filter, the voltage applied to the EA is equal to the voltage of the discharge motor. Then, the key 16 (15) closes according to the signals of the control unit 17, and after a while it again breaks the NC circuit for a few milliseconds, this process is repeated until the breakdown of the EP - K gap occurs, then its conductivity becomes such that the entire current throttle 14 is closed in the ignition circuit, and the diode 19 is locked by a higher potential of the anode. With the duration of the ignition pulse of several milliseconds, the energy stored in the inductor 14 is not enough to form the ignition pulse for this mode (pickup mode), therefore, for the closed state of the key 16 (15), the control unit 17 opens the key 24, through which the output voltage rectifier 13 is supplied to the electric field, since there is no heater current at this moment, and the discharge current has not yet reached the required value, the output 13 will have a constant voltage, i.e. the burning pulse will not have cuts.

As soon as the discharge current reaches a certain value (0.4 from the nominal), according to the signal of the sensor 11, the control unit 17 opens the keys 15, 16, 24, while the cathode is heated and the ignition pulses are stopped. Due to a sharp decrease in the resistance of channel A - K, the discharge voltage drops, its value is determined by the degree of short circuit in the channel, which in turn is proportional to the amount of gas in the discharge chamber. At this moment, one of the cells 4, 5 goes into the mode of limiting the discharge current, due to which the effective value of the voltage at the output of the rectifier 9 decreases. As the excess gas is burned, the resistance of channel A - K increases, the current limitation ceases and the system enters the nominal mode work. The engine is switched off by an external command, by which the master oscillator 3 stops the generation of the control voltage, and the converter cells are locked.

Tests of the layout of the proposed device for starting and powering an electro-jet plasma engine showed that, compared with the prototype, the ripple of the current consumption is three times less, and the maximum power consumption during short circuit in the load is 1.3 times less than in [3] at p = 3 .

LITERATURE

1. Power electronics development for the SPT-100 Thruster / JAHamley, JMHill, JMSankovic // IEPC-93-044, Proceeding of the 23 ^rd International Electric Propulsion Conference, September, 1993.

2. A.S. No. 752664 of the USSR. Voltage converter / A.M. Baranov, M.M. Glibitsky and others // BI. 1980, No. 28.

3. Pat. 2162623 RF. The system for starting and powering an electroreactive plasma engine / I.M.Katasonov // Inventions. 2001, No. 3.

Claims (1)

A device for starting and powering an electro-jet plasma engine, comprising converter cells connected to the output of the input filter, inputs connected to the output of the master oscillator and consisting of switching transistors and transformers, a summing discharge rectifier, the outputs of which are connected through the limiting reactor to the input terminals of the engine, and the rectifier of the cathode heaters the output of which is through the current sensor of the cathode heaters, the metering choke and the controlled keys are connected to heaters of the cathodes of the engine, characterized in that the converter cells are divided into two groups, the ratio of the number of cells in the group that stabilizes the discharge voltage to the number of cells in the group that stabilizes the current of the cathode heater is determined by the ratio of the difference between the maximum and minimum input voltage to the minimum input voltage, the inputs of one group of cells are connected to the outputs of threshold devices, the inputs of which are connected to sensors of current and discharge voltage, and the inputs of another the cells are connected to the outputs of the threshold devices, the inputs of which are connected to the sensors of the discharge current and the current of the cathode heater, the device contains an additional controlled key connecting the output terminal of the metering inductor to the ignition electrode, and its gate is connected to the output of the control unit, to the inputs of which external commands and a signal from a discharge current sensor.

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